JP2000260022A - Production of magnetic recording medium, magnetic recording medium, and silver halide photographic sensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a magnetic recording medium possible to have excellent transparency and slipperiness and to obtain high magnetic output by specifying the shearing rate acting on an upper layer transparent magnetic recording layer coating liquid adjacent onto a lower layer transparent magnetic recording layer coating liquid on a base side to a specified value or a bove and applying two layers of transparent magnetic recording layers in double layers by a wet-on-wet system on one surface on a base. SOLUTION: At the time of the wet-on-wet double layer coating, by increasing the shearing rate of the upper layer transparent magnetic recording layer coating liquid, the thin magnetic recording layers having excellent magnetic characteristics can be obtained. The formation may be achieved by applying the upper layer transparent magnetic recording layer coating liquid faster and thinner than the lower layer transparent magnetic recording layer coating liquid. More specifically, by setting the shearing rate preferably at >=2×104 sec-1, not only the transparent and smaller film thickness can be obtained but the orientability after drying can be improved and the magnetic characteristics can be enhanced as mechanical orientation occurs strongly at the coating application layers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a magnetic recording medium having an optically transparent magnetic recording layer, and a transparent magnetic recording medium produced by the method. More specifically, the present invention relates to a silver halide emulsion layer and a transparent magnetic recording medium. The present invention relates to a silver halide photographic light-sensitive material having a recording layer.

[0002]

2. Description of the Related Art The performance of a magnetic recording medium largely depends on the progress of its coating technology as the density of a magnetic recording increases, and as a result of the progress of multi-layering and thinning. Such advances have recently produced APS silver halide photographic materials having a new magnetic recording layer by combining a magnetic recording medium with a silver halide photographic material. APS is Adva
This is an abbreviation for nused Photo System. This magnetic recording medium and silver halide photographic light-sensitive material
On the magnetic recording layer side of the PS silver halide photographic light-sensitive material, for example, the type such as sensitivity of the silver halide photographic light-sensitive material, the serial number, the manufacturer name, and the emulsion No. Various information about the camera, such as shooting date and time, aperture, exposure time, lighting conditions, filters used, weather, shooting size, shooting model, use of anamorphic lenses, etc., as well as the number of prints and filters Selection, customer's color preference, size of trimming frame, etc. when making prints and inputting various necessary information from customers, etc.
It is also necessary to improve the print quality and the efficiency of the printing operation.

In a conventional silver halide photographic light-sensitive material, it is impossible to input all of these information, and information such as a photographing date, an aperture, and an exposure time is optically input at the time of photographing. It was not too much. In addition, it has been impossible to input the above information into a developed silver halide photographic material at the time of printing.

On the other hand, in the magnetic recording method, since recording and reproduction are easy, a magnetic recording layer is conventionally provided on a silver halide photographic light-sensitive material, and the above-mentioned various information is input. Various technical studies on layers are actively conducted,
Various proposals have been made. For example, it is possible to provide a stripe-shaped magnetic recording layer in which ferromagnetic fine particles are dispersed on the silver halide emulsion layer surface or the back surface next to the image area, and to record information such as sound and photographing conditions. 1975-62
Nos. 627 and 49-4503, U.S. Pat.
As described in JP-A Nos. 43,376 and 3,220,843, magnetic recording has already been performed on silver halide photographic materials. Further, a silver halide photographic light-sensitive material having a transparent magnetic recording layer on the back surface by selecting the amount and size of magnetic particles is disclosed in US Pat.
No. 82,947, No. 4,279,945, No. 4,
302, 523, etc. Also, U.S. Pat. No. 4,947,196, WO 90/04254.
The specification describes a roll-shaped film having a magnetic recording layer on the back surface of a silver halide photographic light-sensitive material, and an imaging camera having a magnetic head.

By providing these transparent magnetic recording layers, it has become possible to record the above-mentioned various kinds of information in a silver halide photographic light-sensitive material, which has been difficult in the past, and to record audio and image signals in the future. It has the potential to do so.

However, the properties required of the transparent magnetic recording layer are higher than those of the conventional magnetic recording medium, such as transparency, water resistance, abrasion resistance, electric characteristics, magnetic characteristics, and slipperiness. The silver halide emulsion layer is required to have a production suitability such as perforation and the like, and to have no influence on the photographic performance of the silver halide emulsion layer.

[0007] Among them, particularly with respect to water resistance and slipperiness, the characteristics are largely different from those of general video tapes and audio tapes. For example, with respect to water resistance, a silver halide photographic light-sensitive material undergoes a series of development processing steps such as processing with an alkaline developer containing a developing chemical, processing with an acidic fixing solution, processing with other stabilizing solutions, washing, and drying. Since the magnetic recording medium passes after photographing, performance such as water resistance and alkali resistance is required as a magnetic recording medium.

Further, the silver halide photographic light-sensitive material has a very high rigidity of the support compared with a video tape or the like.
In order to perform good magnetic recording / reproducing, the magnetic recording layer must be brought into close contact with the magnetic head with a very strong force. Therefore, since the magnetic recording layer is easily damaged by the head, the magnetic recording layer must have excellent slipperiness. Means for solving these problems are disclosed in Japanese Patent Laid-Open No. 7-18 / 1994.
No. 1613. That is, the uppermost layer on the side of the transparent magnetic recording layer of a silver halide photographic light-sensitive material having a transparent magnetic recording layer contains wax having an average particle size of 0.01 to 3 μm and a hydrophobic binder to thereby improve slipperiness and after development. A transparent magnetic recording layer having scratch resistance has been proposed.

On the other hand, the magnetic recording layer of a silver halide photographic material having a transparent magnetic recording layer has transparency that does not affect photographic performance, and allows stable recording and reproduction of magnetic signals without errors. High magnetic performance (magnetic output) that can be performed is required. As a method for obtaining this transparency and high magnetic output, JP-A-9-160173 and JP-A-9-88
No. 283 discloses a dispersion state of a magnetic substance in a magnetic coating solution,
It is stated to increase.

[0010] A conventional magnetic recording medium such as a video contains a high-density magnetic material in a magnetic recording layer. This is to emphasize the electrical characteristics and magnetic characteristics, but in the case of a silver halide photographic light-sensitive material having a magnetic recording layer, since the magnetic recording layer is required to be transparent and have high output,
It cannot be achieved by a technique such as forming a magnetic recording layer of a video. For example, Japanese Patent Application Laid-Open No. 5-329433 discloses a technique in which a magnetic recording layer is formed as two coating liquids by simultaneous multi-layering, but is not suitable for forming a transparent magnetic recording layer. When two or more magnetic recording layer coating liquids are applied in a multi-layered manner, the respective layers are likely to be mixed.

On the other hand, the magnetic recording layer of the silver halide photographic light-sensitive material having a magnetic recording layer is required to have other properties such as transparency which does not affect photographic performance, and errors in recording / reproducing a magnetic recording layer signal. There is a demand for high magnetic performance (magnetic recording layer output) so that the magnetic recording layer can be stably operated without any magnetic field. It is disclosed in Japanese Patent Application Laid-Open Nos. 9-160173 and 9-88283 that the transparency and the output of the magnetic recording layer can be achieved by increasing the dispersion state of the magnetic powder in the coating liquid for the magnetic recording layer. It has been disclosed.

In order to improve the transparency of the magnetic recording layer, the thickness of the magnetic recording layer itself is reduced without changing the amount of magnetic powder per unit volume, or the film thickness per unit volume is kept unchanged. When the amount of the magnetic powder is reduced, the magnetic output of the magnetic recording layer is reduced in proportion to the decrease of the film thickness or the amount of the magnetic powder, and it is difficult to perform stable magnetic recording and reproduction. On the other hand, JP-A-8-15797 describes that a high magnetic output can be obtained by applying a magnetic field to the transparent magnetic recording layer and increasing the orientation ratio of the magnetic powder in the magnetic recording layer. I have.

[0013]

As described above, the magnetic recording layer of a silver halide photographic material has water resistance, scratch resistance,
Various issues have arisen due to transparency, such as slipperiness, transparency, magnetic output, and mixing properties of the upper and lower layers by multi-layer coating, development of silver halide photographic materials, and magnetic input / output reproduction processing. .

A first object of the present invention is to provide a method for manufacturing a magnetic recording medium having excellent transparency and slipperiness and having a high magnetic output.

A second object of the present invention is to provide a wet-on
An object of the present invention is to provide a method of manufacturing a magnetic recording medium by multilayer coating of a transparent magnetic recording layer in which mixing between multilayers does not occur during wet multilayer coating.

A third object of the present invention is to provide a magnetic recording medium manufactured by the above method.

A fourth object of the present invention is to provide a silver halide photographic material having the above-mentioned transparent magnetic recording layer.

[0018]

The present invention comprises the following constitutions.

(1) When at least two transparent magnetic recording layers are coated on one surface of the support by a wet-on-wet method, the transparent magnetic recording layers are adjacent to the lower transparent magnetic recording layer coating solution on the support side. A method for producing a magnetic recording medium, wherein the application is performed at a shear rate of 2 × 10 ⁴ sec ^-1 or more.

(2) In a method for producing a magnetic recording medium having at least two transparent magnetic recording layers on one surface of a support, an upper layer adjacent to the lower transparent magnetic recording layer coating solution on the support side. Wet on transparent magnetic recording layer coating solution
A method for manufacturing a magnetic recording medium, wherein the orientation ratio of the magnetic powder in the upper transparent magnetic recording layer is made higher than the orientation ratio of the magnetic powder in the lower transparent magnetic recording layer by multi-layer coating by a wet method.

(3) The method for manufacturing a magnetic recording medium according to (1), wherein the orientation ratio of the magnetic powder in the upper transparent magnetic recording layer is higher than the orientation ratio of the magnetic powder in the lower transparent magnetic recording layer.

(4) When at least two transparent magnetic recording layers are simultaneously coated on one surface of the support, the viscosity of the lower transparent magnetic recording layer coating solution applied on the side close to the support is sheared. not less than 60cps at a rate 15 sec ^-1, and the production of a magnetic recording medium characterized by applying the viscosity of the upper transparent magnetic recording layer coating solution with adjacent to the air side as 10cps or more when the shear rate of 15 sec ^-1 Method.

(5) The method for producing a magnetic recording medium according to (4), wherein the application is performed at a shear rate of 2 × 10 ⁴ sec ⁻¹ or more for the coating liquid for the upper transparent magnetic recording layer.

(6) The method of manufacturing a magnetic recording medium according to (5), wherein the orientation ratio of the magnetic powder in the upper transparent magnetic recording layer is higher than the orientation ratio of the magnetic powder in the lower transparent magnetic recording layer.

(7) The coating liquid for the upper and lower transparent magnetic recording layers is applied so that the dry thickness of the upper transparent magnetic recording layer is 1 to 30% of the dry thickness of the entire magnetic recording layer. The method for manufacturing a magnetic recording medium according to any one of (1) to (6).

(8) The method for manufacturing a magnetic recording medium according to any one of (1) to (7), wherein the upper transparent magnetic recording layer is an upper transparent magnetic recording layer containing wax. .

(9) The method for manufacturing a magnetic recording medium according to (8), wherein the upper transparent magnetic recording layer containing the wax forms an uppermost layer.

(10) An upper transparent magnetic recording layer coating solution containing a wax adjacent to the lower transparent magnetic recording layer coating solution on the support side is coated on the support in a wet-on-wet manner. A method for manufacturing a magnetic recording medium.

(11) A magnetic recording medium manufactured by the method according to any one of (1) to (10).

(12) A silver halide photographic light-sensitive material having a silver halide emulsion layer on the side of the support opposite to the side having the magnetic recording layer of the magnetic recording medium according to (11).

The present invention will be described in detail.

First, the meaning of transparency of the transparent magnetic recording layer of the present invention will be described. The term “transparent” in the present invention specifically means that the optical density of the magnetic recording layer is 1.5 or less (the measuring method will be described later). In the present invention, the optical density is
Considering the influence on the photograph, it is desirable that the size be small.
It is 2 or less, particularly preferably 0.1 or less.

In the present invention, the term “support side” or “air side” is used to abbreviate the layer on the support at the position of the layer on the support. May be used.

In the constitution (1) of the present invention, the present inventor diligently studied the shearing rate with respect to the coating performance, magnetic properties, etc. of the coating liquid for the upper transparent magnetic recording layer in the wet-on-wet multilayer coating. As a result, the inventors have found that a magnetic recording layer having excellent magnetic properties can be obtained thinly by increasing the shear rate of the upper layer. In the case of simultaneous wet-on-wet multi-layering, the upper layer coating solution is applied thinner and faster than that of the lower layer (1)
Is achieved. The shear rate is given by the Navier-Stokes equation of the following equation, and it can be seen that the shear rate can be increased by applying the denominator, that is, the total flow rate is very small. In the configuration (1), specifically, by setting the shear rate to 2 × 10 ⁴ sec ⁻¹ or more, not only transparency and thinning can be obtained, but also mechanical orientation occurs strongly in the coating layer. The subsequent orientation is improved, and the magnetic properties can be improved. The shear rate is almost 1 × 10 ⁶ sec ⁻¹ , although it varies somewhat depending on the tension of the support during coating, the coating speed, the rigidity of the support, the viscosity of the coating solution, and the like.
The upper limit is about 2 × 10 ⁴ to 1 in the present invention.
It is preferably about × 10 ⁶ sec ⁻¹ . When the shear rate is 2
If it is less than × 10 ⁴ , the magnetic properties (the orientation ratio of the configuration (2)) are inferior.

(Shearing rate) = (coating rate) ² × (coating width) / 2 / (total flow rate) The wet-on-wet multi-layer coating method includes:
There are roughly two methods. One is a method in which two or more layers are coated simultaneously with one coater having two or more slits in one coater. The other one is to apply a lower layer coating solution once and then coat the upper layer while the lower layer is wet. Another method of applying a coating liquid is an overlay method. As a simultaneous multi-layer coating machine, see
Extrusion coaters and curtain coaters described in JP-A-192627 and JP-A-5-329433 are preferred devices. As a coater to be layered at another position, use a usual coater for applying a single layer such as an extrusion coater, an air doctor coater, a gravure coater, a blade coater, an air knife coater, a reverse coater, a slide coater, a spray coater, and a kiss coater However, when an upper layer coating solution is overlaid on a wet lower layer, an extrusion coater having a single slit is preferred. For example, a coating machine described in JP-A-5-329433 is preferably used.

According to the constitution (2) of the present invention, the orientation ratio of the magnetic powder in the lower transparent magnetic recording layer on the support side of the magnetic recording medium having at least two transparent magnetic recording layers on one surface of the support. In this method, the magnetic characteristics are improved by increasing the orientation ratio of the magnetic powder in the upper transparent magnetic recording layer on the air side adjacent thereto.

JP-A-8-15797 discloses that a magnetic recording medium having a limited amount and thickness of magnetic powder, such as a transparent magnetic recording layer, can increase the magnetic input / output by another method. This is a method of increasing the orientation ratio of the magnetic powder in the magnetic recording layer. As a method of increasing the orientation of the magnetic powder, a method of applying a magnetic field orientation with an orientation magnet is generally used.

The present inventors have obtained a magnetic recording medium having a high magnetic input / output by increasing the orientation ratio of the upper layer of the transparent magnetic recording layer coated with the multilayer to that of the lower layer. It has been found that the orientation ratio becomes dominant. Then, it is easier to apply the upper layer having a high orientation ratio when the upper and lower layers are applied by the wet-on-dry method than by the wet-on-dry method. A magnetic recording medium can be obtained. It has also been found that it is important that a layer having a high orientation ratio is in the uppermost layer (contact with the magnetic head).

Here, the orientation ratio will be described. In the present invention, the orientation ratio refers to a cross section that is horizontal to the surface of the support (which is nonmagnetic) and is 4 to the longitudinal direction of the support.
It represents the ratio of magnetic powder oriented in a direction of 5 ° or less, more specifically, acicular magnetic powder to all acicular magnetic powders. That is,
An orientation ratio of 50% indicates a non-oriented state, and an orientation ratio of more than 50% indicates that the film is oriented in the longitudinal direction. The orientation ratio is preferably 55% or more, and particularly preferably 60%. It is preferable that it is above. Incidentally, the orientation ratio of a conventional magnetic recording medium is roughly 55 to 65% depending on the magnetic field orientation for an audio tape, 60 to 70% for a video tape, and 50% for non-orientation for a floppy disk.

The orientation ratio is measured by observing the surface of the magnetic recording layer with a scanning electron microscope. This photograph is processed by an image analyzer, and the observation position is changed, and the processing is performed for 10 or more visual fields to obtain an orientation distribution. When there are two upper and lower layers, the lower magnetic recording layer is polished to remove the lower magnetic recording layer, the lower magnetic recording layer is exposed, and photographing is performed in the same manner.

Next, a method for measuring the orientation distribution will be described. In a region around an arbitrary point P of the symmetric sample,
The standard deviation S (θ) of the pixel values of the entire area is given by the following equation (1).

[0042]

(Equation 1)

If a large number of particles are oriented, it is considered that the difference between the standard deviation in that direction and the other direction is large. Therefore, the difference between S (θ) and the standard deviation in the measurement direction is calculated, and the sum is defined as G1 (θ). The following equation 2 shows G1 (θ). This was normalized and the orientation ratio for each direction was determined.

[0044]

(Equation 2)

For details on the orientation distribution, see "Development of Fiber Orientation Distribution Measurement Method for Fiber Reinforced Plastic" (Kyoto Institute of Technology, Yasushi Hamada, 41st Annual Meeting of the Japan Textile Machinery Society (June 9, 1988) Day)).

In Japanese Patent Application Laid-Open No. 6-274855, in order to make the orientation ratio of the needle-like nonmagnetic powder or magnetic powder in the layer 55% or more, a force is applied to the coating film and the distance between the support and the coater is increased. It can be obtained by adjusting the coating speed, the pressure of the coater against the support, and the like, but no specific method, numerical value, or the like is given. The present inventor has further studied, and has further found a method of giving an orientation ratio as intended in a wet-on-wet multi-layer coating, particularly in the case of simultaneous multi-layer coating.

Further, while the upper and lower layers are wet after the simultaneous layering, the orientation ratio may be increased by applying magnetic field orientation to such an extent that the upper and lower layers do not become the same. The degree of wetting of the coating layer at the time of magnetic field alignment depends on the solvent content of the coating liquid being 1%.
The amount is preferably in the range of 5 to 55% by weight, and preferably 20 to 55% by weight.
４０40% by weight.

The magnetic flux density when performing magnetic field orientation is 50 to 20.
00 Gauss is preferred. The magnetic field orientation can be performed by a permanent magnet, a solenoid, or the like. When a permanent magnet is used, the permanent magnets of the N poles may be arranged to face each other, and the support may be passed between them. The strength of the permanent magnet used is preferably at least 1000 Gauss, but the magnetic recording layer on the support preferably has a magnetic flux density of 50 to 2000 Gauss, preferably 500 to 2000 Gauss. The magnetic flux density applied to the magnetic recording layer can be changed by changing the magnetic field strength of the magnet itself or the distance between the support and the magnet. The orientation magnet may be provided in two or more stages, and the orientation ratio can be further increased.

The configuration (3) according to the present invention has a wet-on
Construct upper layer coating solution when layering by wet method (1)
In this method, the orientation ratio of the upper transparent magnetic recording layer is made higher than that of the lower transparent magnetic recording layer by applying the composition at a shear rate of 2 × 10 ⁴ sec ⁻¹ or more. In order to increase the orientation ratio of the upper layer to 50% or more, it is possible to easily obtain the shear rate in such a manner as to form the upper layer.

The constitution (4) of the present invention relates to the relationship between the viscosities of the upper and lower transparent magnetic recording layer coating solutions at a certain shear rate when two or more transparent magnetic recording layer coating solutions are simultaneously layered. Shear rate of lower transparent magnetic recording layer coating solution 15
When the viscosity at the time of sec ^-1 is 60 cps or more, and the viscosity at the shear rate of 15 sec ^-1 of the coating liquid for the upper transparent magnetic recording layer is 10 cps or more, mixing of the upper and lower layer coating liquids hardly occurs, and It has been found that simultaneous coating can be performed while maintaining the properties. Conversely, when simultaneously layering the upper layer coating solution, the viscosity at a shear rate of 15 sec ^-1 is lower than 60 cps, regardless of whether the upper and lower layer coating solution is a Newtonian fluid or a non-Newtonian fluid. If the other is less than 10 cps, the upper and lower layer coating liquids are mixed.

The viscosity of the coating solution at a shear rate of 15 sec ^-1 in the present invention is measured by a BL viscometer (manufactured by Tokimec Co., Ltd.). Viscosity of about 10 to 10000
In the case of cps, No. 1 to 4 rotor rotation speed 60r
In the case of about 10 cps or less, it can be measured at a rotation speed of 12 rpm using a BL adapter. However, the viscosity measurement method is not particularly limited as long as the viscosity can be measured at a shear rate of 15 sec ^-1 .

In the constitution (5) of the present invention, the upper and lower coating liquids having the viscosity of the constitution (4) are subjected to wet-on-wet multi-layer coating of the coating liquid for the upper magnetic recording layer, particularly to shearing when simultaneously layering. By increasing the speed to 2 × 10 ⁴ sec ⁻¹ or more, the upper transparent magnetic recording layer can be made thinner, and magnetic output (electromagnetic wave conversion characteristics), transparency, and the like can be further improved.

In the constitution (6) of the present invention, the orientation ratio of the upper transparent magnetic recording layer is made higher than the orientation ratio of the lower transparent magnetic recording layer by the constitution (5). When the viscosity of the upper and lower layer coating liquids is set to 10 cps or more and 60 cps or more when the shear rate is 15 sec ^-1 , the upper layer coating liquid is sheared so as to prevent mixing of the liquids and raise the orientation ratio of the upper and lower layers. By setting the speed to 2 × 10 ⁴ sec ⁻¹ or more, it is possible to obtain a magnetic recording medium having more excellent magnetic properties than the configuration (5).

The structure (7) of the present invention comprises the structures (1) to (6)
By using the above method, the dry film thickness of the upper transparent magnetic recording layer is set to 1 to 30% with respect to the dry film thickness of the entire transparent magnetic recording layer on the support as a finishing layer constitution. And the orientation ratio can be further satisfied. That is, by using the upper transparent magnetic recording layer coating solution viscosity when more than 10cps shear rate 15 sec ^-1, the lower transparent magnetic recording layer coating solution viscosity of more than 60cps at a shear rate of 15 sec ^-1, the finished With the dry film thickness of the entire magnetic recording layer being 1% to 30% of the dry film thickness of the upper layer, the upper layer coating solution is subjected to simultaneous multilayer coating adjacent to the lower layer coating solution at a shear rate of 2 × 10 ⁴ sec ⁻¹ or more. By doing so, a magnetic recording medium having a thinner film and excellent magnetic properties can be obtained. The total dry film thickness of the transparent magnetic recording layer in the invention is preferably from 0.2 to 10 μm, more preferably from 0.4 to 2 μm. inside that,
The thicker the upper transparent magnetic recording layer is, the better the magnetic input / output is.

In the constitutions (8) to (10) of the present invention, the upper layer is a transparent magnetic recording layer containing wax, and
This is a method for producing a magnetic recording medium by the method described in (7).

In general, a transparent magnetic recording layer is inferior to a magnetic recording layer of a conventional magnetic recording medium in magnetic recording ability.
In order to accurately record information on the magnetic recording layer, it is necessary to impart a sliding property to the magnetic recording medium so as not to cause noise, dropout, abrasion, running failure and the like.
However, usually, the above-mentioned drawback is covered by providing a wax-containing layer containing no magnetic powder on the upper layer, especially on the uppermost layer, but it can be said that it is a method that sacrifices magnetic properties. That is, a layer containing no magnetic powder is provided closest to the magnetic head. After applying the transparent magnetic recording layer, the upper layer (especially the uppermost layer)
In particular, when a coating liquid of a transparent magnetic recording layer containing a wax is applied thinly by a wet-on-dry method, coating slippage, coating unevenness, liquid dripping, etc. occur, making it difficult to apply the coating uniformly, and technically producing a transparent magnetic recording medium. Regarding the problem, the present inventor applied a lower transparent magnetic recording layer coating solution and a wax-containing upper transparent magnetic recording layer in a wet-on-wet manner to form a thin wax-containing upper transparent magnetic recording layer into a lower transparent magnetic recording layer. It was successfully provided on the recording layer.

The constitutions (8) to (10) of the present invention can be obtained by applying the coating liquid for the wax-containing upper transparent magnetic recording layer in a multi-layer manner by a wet-on-wet method by the method of the constitutions (1) to (7). Stabilize coating, uniform, thin film, good transparency, moderate slipperiness, scratch resistance, and magnetic recording layer can directly contact magnetic head, magnetic input / output characteristics Is a method by which an excellent magnetic recording medium can be obtained. In the present invention, the object has been achieved by making the wax-containing upper transparent magnetic recording layer the uppermost layer. Configurations (8) to (10) of the present invention include:
This is the most preferred embodiment in the present invention.

The structure (11) according to the present invention has the structure (1) to the structure (1).
A magnetic recording medium manufactured by the method of (10). The constitution (12) of the present invention is a silver halide photographic light-sensitive material having at least one silver halide emulsion layer on a support opposite to the magnetic recording layer side of the magnetic recording medium of the constitution (11).

Next, the transparent magnetic recording layer, the wax-containing transparent magnetic recording layer, the magnetic recording medium and the materials used for them will be described in more detail.

The ferromagnetic fine powder used for the transparent magnetic recording layer includes ferromagnetic iron oxide fine powder, cobalt-doped ferromagnetic iron oxide fine powder, ferromagnetic chromium dioxide fine powder, ferromagnetic metal powder, and ferromagnetic alloy powder. And barium ferrite (hereinafter, magnetic powder may be referred to as magnetic powder).

The ferromagnetic powder can be produced according to a known method. Examples of the shape include a needle shape, a rice grain shape, a spherical shape, a cubic shape, and a plate shape, but in the present invention, from the viewpoint of the orientation ratio, the ferromagnetic powder is limited to the one having an axis ratio of 2 or more. Is done. The axis ratio here is the ratio of the major axis diameter to the minor axis diameter (major axis diameter / minor axis diameter). The minor axis diameter and the major axis diameter are average values of the minor axis diameter and the major axis diameter of 500 ferromagnetic powders measured by a transmission electron micrograph. Preferably, the axial ratio is between 5 and 15. The crystallite size and non-surface area are not particularly limited, but the crystallite size is 400 ° or less,
Preferably at least 20 m ² / g in SBET, and particularly preferably equal to or greater than 30 m ² / g.

The pH of the ferromagnetic powder is not particularly limited, but a preferable pH range is 5-10. The ratio of divalent iron / trivalent iron in the ferromagnetic iron oxide fine powder is not particularly limited. Examples of magnetic recording layers using these ferromagnetic powders are described in JP-A-47-32812 and JP-A-53-1.
No. 09604.

The Hc (coercive force) of the ferromagnetic powder is not particularly limited, but is preferably 400 to 2000 Oe.

The preferred use amount of the magnetic powder is at least 4 × 10 ^-4 g per m ^{2 of the} silver halide photographic light-sensitive material. The upper limit is not particularly limited as long as the optical density of the light having a wavelength of 436 nm is 1.5 or less, preferably 0.1 or less. However, the limit is about 1 g per 1 m ^2. I do.

In order to stably form the transparent magnetic recording layer, the binder is preferably used in an amount of 1 to 200 parts by weight, more preferably 2 to 50 parts by weight, per 1 part by weight of the magnetic powder.

In order to firmly adhere the transparent magnetic recording layer on the support, an undercoat layer may be provided on the support, and the support may be subjected to chemical treatment, mechanical treatment, corona discharge treatment, flame treatment, or the like. A surface activation treatment such as an ultraviolet treatment, a high frequency treatment, a glow discharge treatment, a discharge plasma treatment in an inert gas, a laser treatment, a concentrated acid treatment, and an ozone oxidation treatment may be performed. Furthermore,
After the surface activation treatment, an undercoat layer may be provided. The undercoat layer is preferably of an aqueous latex type.

The hydrophobic binder used in the transparent magnetic recording layer of the present invention includes a thermoplastic resin, a radiation-curable resin, a thermosetting resin, and other reactive resins, and is dissolved or dispersed in an organic solvent or water. Can be used.

Examples of the thermoplastic resin include vinyl chloride-vinyl acetate copolymer, vinyl chloride resin, vinyl acetate resin, vinyl acetate-vinyl alcohol copolymer, partially hydrolyzed vinyl chloride-vinyl acetate copolymer, and vinyl chloride. -Vinyl polymers such as vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, ethylene-vinyl alcohol copolymer, chlorinated polyvinyl chloride, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, etc. Or a copolymer, a cellulose derivative such as a cellulose nitrate, a cellulose diacetate, a cellulose acetate propionate, a cellulose acetate butyrate resin, a copolymer of maleic acid and / or acrylic acid, an acrylate copolymer, and acrylonitrile- Styrene copolymer, chlorinated poly Tylene, acrylonitrile-chlorinated polyethylene-styrene terpolymer, methyl methacrylate-butadiene-styrene terpolymer, acrylic resin, polyvinyl acetal resin, polyvinyl butyral resin, polyester polyurethane resin, polyether polyurethane resin, polycarbonate polyurethane resin And a rubber-based resin such as a polyester resin, a polyether resin, a polyamide resin, an amino resin, a styrene-butadiene resin, a butadiene-acrylonitrile resin, a silicone-based resin, and a fluorine-based resin. Particularly, cellulose derivatives, especially cellulose diacetate, are preferred.

The thermoplastic resin has a Tg (glass transition point) of -40 to 180 ° C., preferably -30 to 150 ° C. The weight average molecular weight is 500
It is preferably from 0 to 300,000, and more preferably from 10,000 to
200,000 is preferred. In the transparent magnetic recording layer of the present invention, it is preferable to use a combination of a thermoplastic resin having a Tg of 50 ° C. or higher and a thermoplastic resin having a Tg of 30 ° C. or lower. Tg
Is described in detail in New Experimental Chemistry Course 19, Polymer Chemistry II (Maruzen).

The above resin may be used as a solution in a solvent, but may also be used as an aqueous emulsion or an aqueous colloid solution. In the case of an aqueous emulsion, the particles preferably have a particle size of 5 nm to 2 μm.

The radiation-curable resin is a resin which is cured by radiation such as an electron beam or an ultraviolet ray, and includes a maleic anhydride type, a urethane acrylic type, an ether acrylic type, and an epoxy acrylic type.

Examples of the thermosetting resin and other reactive resins include a phenol resin, an epoxy resin, a polyurethane-based curing resin, a urea resin, an alkyd resin, and a silicone-based curing resin.

The hydrophobic binders listed above may have a polar group in the molecule. Examples of the polar group include an epoxy group, -COOM, -OH, -NR ₂ , -NR ₃ X,- SO
_{3 M, -OSO 3 M, -PO} 3 M 2, -OPO 3 M ( wherein, M is each a hydrogen atom, an alkali metal or ammonium, X is an acid which forms an amine salt, each R is a hydrogen atom, Which represents an alkyl group).

The above-mentioned binder can be cured by using a known crosslinking agent of epoxy type, aziridine type or isocyanate type, or by using a radiation-curable resin monomer in combination. As the isocyanate-based crosslinking agent, a polyisocyanate compound having two or more isocyanate groups, for example, tolylene diisocyanate, 4,4'-
Isocyanates such as diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, naphthylene-1,5-diisocyanate, o-toluidine diisocyanate, isophorone diisocyanate, and reaction products of these isocyanates with polyalcohols (for example, tolylene diisocyanate 3 And a polyisocyanate formed by condensation of these isocyanates.
Specifically, Coronate 3041, Millionate 400
(Nippon Polyurethane).

In the transparent magnetic recording layer of the present invention, a hydrophobic binder and a hydrophilic binder can be used in combination, but the transparent magnetic recording layer is affected by the development of a silver halide photographic material. Preferably, the amount of hydrophilic binder is less than or equal to 5% by weight, based on the amount of hydrophobic binder. Examples of the hydrophilic binder include Research Disclosure (RD) No. No. 17643, p. 18
Examples include water-soluble polymers, cellulose ethers, latex polymers, and water-soluble polyesters described on pages 716 and 651.

Examples of the water-soluble polymer include gelatin, gelatin derivatives, casein, agar, sodium alginate,
Starch, polyvinyl alcohol, acrylic acid-based copolymer, maleic anhydride copolymer, and the like, and cellulose ethers include methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose.

When a water-soluble polymer is used, it is preferable to use a hardener used in a silver halide photographic material. Examples of the hardener include aldehyde compounds, ketone compounds, compounds having a reactive halogen, compounds having a reactive olefin, N-methylol compounds, isocyanates, aziridine compounds, acid derivatives, and epoxy compounds. , Mucohaloacids, chromium alum, zirconium sulfate, carboxyl group activated hardener and the like. The hardener is usually preferably used in an amount of about 0.01 to 60% by weight based on the water-soluble polymer.
Preferably it is 0.05 to 50% by weight.

The wax that can be used in the wax-containing transparent magnetic recording layer of the present invention includes carnauba wax, candelilla wax, rice wax, wood wax,
Beeswax, montan wax, ozokerite, ceresin, paraffin wax, polyethylene wax, silicone oil such as polysiloxane, fluorine-containing compounds, higher fatty acids, higher fatty acid esters, higher alcohols, higher alcohol esters, and the like. Alternatively, they can be used in combination.

The form of the wax is not particularly limited, such as solids, liquids, and aqueous dispersions (emulsions). When the wax elutes from the transparent magnetic recording layer due to heating during the development processing of the silver halide photographic light-sensitive material, the developer The wax preferably has a melting point of 38 ° C. or more, more preferably 50 ° C. or more from the viewpoint of storage characteristics and the like. From the viewpoint of easy handling, those having a temperature of 150 ° C. or lower are preferred.

The amount of the wax to be added is not particularly limited, but is preferably 0.1 to 50% by weight, more preferably 2 to 1% by weight, based on the weight of the binder of the transparent magnetic recording layer, from the viewpoint of appropriate slip properties and transparency.
0% by weight is preferred.

The average particle size of the wax in the transparent magnetic recording layer is preferably 0.01 to 3 μm, although it depends on the thickness of the transparent magnetic recording layer in order to provide sufficient slipperiness. 0.05-1 μm is preferred.

The method of adding the wax to the coating liquid for the transparent magnetic recording layer is not particularly limited. As a specific example, the wax is heated and dissolved in a solvent, then cooled and precipitated to form a suspension or emulsion in the solvent. A method of preparing a wax liquid in a form, a method of dissolving a wax in a solvent having a high solubility, adding a solvent having a low solubility to precipitate the liquid, and preparing a wax liquid in a form of a suspension or an emulsion in the solvent. Alternatively, there is a method in which a wax is pulverized by mechanical shearing force using a dispersing machine for preparing a coating liquid for a magnetic recording layer, and a wax liquid is prepared in the form of a suspension or emulsion in a solvent. The suspension or emulsion in the solvent obtained by the above method is added to the coating solution for the transparent magnetic recording layer, and the wax particles are uniformly dispersed in the coating solution for the transparent magnetic recording layer by a disperser, and the transparent magnetic recording containing wax is contained. Prepare a layer coating solution. At this time, the average particle size of the wax can be controlled by the method of preparing the suspension or emulsion in a solvent or the dispersion conditions after addition to the coating solution for the magnetic recording layer. Specific examples of the dispersion conditions depend on the magnitude and time of the shearing force, such as the type of the dispersing machine, the type, size, and filling rate of the dispersion medium, and the dispersion time. When the shearing force required for dispersion is large and the dispersion time is long, the average particle size of the wax becomes small.
In order to mix and disperse these wax liquids in the coating liquid for the transparent magnetic recording layer, an appropriate disperser may be used.

The wax particles in the coating solution have a maximum thickness of 3 μm as described above, and after coating as a wax-containing upper transparent magnetic recording layer, the upper layer is heated to a temperature higher than the melting point of the wax and the T of the support.
g or less of hot air may be blown, or the layer may be brought into contact with a roller heated to a temperature equal to or higher than its melting point, or heat treatment using both of them may be performed. In the present invention, it is preferable that the treatment is carried out while being conveyed at a roller heated to a temperature not lower than the melting point, for example, at 100 ° C., so that the shape of the wax particles is deformed to make the slipperiness appropriate. In addition, it is possible to improve the smoothness by calendering this layer and further improve the S / N ratio of the magnetic output. In the case of a silver halide photographic material, the silver halide emulsion layer is coated
It is applied after calendering.

The coating solution of the transparent magnetic recording layer of the present invention contains various additives such as an antistatic agent, an antiadhesive agent, an agent for improving friction or abrasion resistance, a dispersant, a plasticizer, an abrasive, and a matting agent. Can be added.

Examples of the abrasive include non-magnetic inorganic powders having a Mohs hardness of 5 or more, preferably 6 or more. Specifically, aluminum oxide (α-alumina, γ-alumina, corundum, etc.), chromium oxide (Cr ₂ O ₃ ), iron oxide (α-Fe ₂ O ₃ ), oxides such as silicon dioxide and titanium dioxide, carbides such as silicon carbide and titanium carbide, and fine powders such as diamond. The average particle size is preferably 0.01 to 2.0 μm, and can be added in the range of 0.5 to 300 parts by weight based on 100 parts by weight of the magnetic powder.

As the antistatic agent, fine particles of metal oxide are preferable. Oxygen-excess oxide such as Specific examples _{Nb 2 O 5 + x, RhO} 2-x, nonstoichiometric hydrides such as Ir ₂ O oxygen deficiency oxides such as _3-x, or Ni (OH) _x ,
HfO ₂ , ThO ₂ , ZrO ₂ , CeO ₂ , ZnO, TiO
₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO,
BaO, MoO ₂ , V ₂ O ₅ or the like, or a composite oxide thereof is preferable, and ZnO, TiO ₂ and SnO ₂ are particularly preferable. Examples of including heteroatoms include, for example, addition of Al, In or the like to ZnO, and Nb or T to TiO ₂ .
The addition of a and the like, and the addition of Sb, Nb, a halogen element and the like to SnO ₂ are effective. The addition amount of these different atoms is preferably in the range of 0.01 to 25 mol%,
A range of 0.1 to 15 mol% is particularly preferred.

The volume resistivity of these conductive metal oxide powders is preferably 10 ⁷ Ωcm, particularly preferably 10 ⁵ Ωcm or less. Alternatively, a sol in which the metal oxide fine particles are mixed in an aqueous solution may be used.

In addition, conductive fine powders such as carbon black and carbon black graft polymer, nonionic surfactants such as alkylene oxide, glycerin and glycidol; higher alkylamines, quaternary ammonium salts, pyridine Other salts of heterocyclic compounds, cationic surfactants such as phosphonium or sulfoniums; anionic surfactants containing acidic groups such as carboxyl group, phosphate group, sulfate group, phosphate group; amino acids, aminosulfone Examples include amphoteric surfactants such as acids and sulfuric acid and phosphoric esters of amino alcohol. Incidentally, the surfactant may be contained as a substituent of the polymer. These antistatic agents may be added to the magnetic recording layer, or may be provided as a single layer below the transparent magnetic recording layer.

The mat material is not particularly limited, and may be an inorganic or organic material, or a mixture of two or more.
Examples of the inorganic matting agent include silicon dioxide, aluminum oxide, barium sulfate, manganese colloid, titanium dioxide, strontium barium sulfate, and the like. The organic matting agent is preferably fine polymer beads. Examples of the monomer used for the organic matting agent include polymers or copolymers of acrylic esters, acrylic acids, styrenes, vinyl esters, and the like. It is also preferable to add a crosslinking agent such as divinylbenzene or N, N'-methylenebisacrylamide to form a copolymer having a three-dimensional network structure.

Solvents used in the coating solution of the transparent magnetic recording layer of the present invention include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, tetrahydrofuran, methanol, ethanol, propanol, butanol, isobutyl alcohol, isopropyl alcohol in any ratio. , Methylcyclohexanol, methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isopropyl acetate, ethyl lactate, glycol acetate, monoethyl ether, ether, glycol dimethyl ether, glycol monoethyl ether, dioxane, benzene, toluene, xylene, cresol, Chlorobenzene, styrene, methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, dichlor Benzene, N, N-dimethylformamide, hexane, water or the like, can be used without any limitation.

The method for dispersing the coating liquid for the transparent magnetic recording layer of the present invention is not particularly limited, but a usual dispersing machine such as a two-roll mill, a three-roll mill, a ball mill, an attritor, a sand mill, an annular sand mill, High-speed impeller, kneader, high-speed disper, twin-screw extruder, homogenizer, ultrasonic disperser, mixer,
A blender or the like can be used.

Next, the silver halide photographic light-sensitive material will be described.

The silver halide emulsion layer used in the silver halide photographic light-sensitive material includes a silver halide emulsion layer for X-rays,
Examples thereof include a silver halide emulsion layer for a printing light-sensitive material, a negative color silver halide emulsion layer, a positive color silver halide emulsion layer, and a silver halide emulsion layer for thermal development. These silver halide emulsion layers may be a single layer, or two or more emulsion layers may be laminated. For example, there are at least six or more silver halide emulsion layers for color negative. These multilayer silver halide emulsion layers are often laminated with a non-photosensitive layer interposed therebetween. The constituent layers other than the silver halide emulsion layer include an antihalation layer, a crossover light cut layer, an ultraviolet protection layer, an intermediate layer, a protective layer, an upper protective layer, an antistatic layer, a light absorption layer, a back layer, and a back layer. An upper layer and the like can be mentioned. These layers are combined with the silver halide emulsion layer depending on the application,
A multilayer silver halide photographic light-sensitive material is constituted.

The silver halide emulsion of the silver halide photographic light-sensitive material according to the present invention may be, for example, Research Disclosure (hereinafter abbreviated as "RD" or "No.") 17
643, pp. 22-23 (December 1978) "I. Emulsion Preparation a
nd Types) ”and pp. 18716, 648, Grafkid,“ Physics and Chemistry of Photography ”, published by Paul Montel (P. Glafkides, Chimique et al.).
Physique Photographique, P
aul Montel, 1967), Duffin, Photographic Emulsion Chemistry, published by Focal Press (GF Duffi).
n, Photographic Emulsion C
hemistry, Focal Press 196
6), Zerikman et al., "Production and Coating of Photographic Emulsion", published by Focal Press (VL Zelikman et al.
Making and Coating Photog
raphic Emulsion, Focal Pre
ss, 1964).

The emulsion is disclosed in US Pat. No. 3,574,628,
No. 3,665,394 and British Patent 1,413,7
The monodisperse emulsion described in JP-B-48 is also preferred.

The silver halide emulsion can be subjected to physical ripening, chemical ripening and spectral sensitization. Additives used in such a process are described in RD 17643, 18716 and 308119.

When the silver halide photographic light-sensitive material of the present invention is a silver halide color photographic light-sensitive material, photographic additives which can be used are also described in the above RD. In addition, various couplers can be used, and specific examples thereof are also described in RD17643 and RD308119.

Further, these additives are referred to as RD30811.
It can be added to the photographic photosensitive layer by the dispersion method described in page 9, page 7, page XIV, section XIV.

The silver halide color photographic light-sensitive material can be provided with an auxiliary layer such as a filter layer or an intermediate layer described in RD308119 and II-K.

When the silver halide color photographic light-sensitive material is constituted, various layer constitutions such as a forward layer, a reverse layer and a unit constitution described in the above-mentioned RD308119, section VII-K can be employed.

To develop the silver halide photographic light-sensitive material of the present invention, for example, T.I. H. James, Theory of the Photographic Process, 4th Edition (The Theory of The Photog
raphic ProcessFourth Edit
ion), pages 291-334, and the Journal of the American Chemical Society (Journal)
of the American Chemical
Society) 73, 3,100 (195
Known developers described in 1) can be used. In addition, the color photographic light-sensitive material uses the above-mentioned R
D17643, pages 28 to 29, RD18716, 615
The image can be developed by the usual method described on page RD308119, XIX.

The support used in the magnetic recording medium or silver halide photographic light-sensitive material of the present invention includes polyethylene terephthalate (PET), polyethylene naphthalate (PEN), cellulose triacetate (TAC) film, polycarbonate film, polystyrene film, A support that can be used for a conventional magnetic recording medium such as a polyolefin film or a silver halide photographic light-sensitive material can be used without limitation.

Since the silver halide photographic light-sensitive material is kept wound in the patrone for a long time, it tends to have a curl. When a cellulose triacetate film is used as a support, the curl attached after the development processing is recovered, but in the case of a polyethylene terephthalate film, the curl is hard to recover even after the development. Therefore, a modified polyester film having a curl recovery property is disclosed in JP-A-1-244446,
No. 1-291248, No. 1-298350, No. 2-
No. 89045, No. 2-93641, No. 2-18174
No. 9, 2-214852, 2-291135 and the like. The modified polyester incorporates, for example, a component having a high water content such as a polar group or a substituent in the polyester, and it is also preferable to use such a modified polyester film.

On the support, there are provided a matting agent, an antistatic agent, a lubricant, a surfactant, a stabilizer, a dispersant, a plasticizer, an ultraviolet absorber, a conductive substance, a tackifier, a softener, and a fluidizer. , A thickener, an antioxidant, a dye preventing light piping phenomenon, and the like.

The light piping phenomenon is a phenomenon in which light enters a film coated with a silver halide emulsion layer from an edge to cause a fogging phenomenon in the silver halide emulsion layer. To prevent the phenomenon, a dye is contained. Is good. The type of the light-piping phenomenon preventing dye is not particularly limited, but when a polyester film is used as the support, a dye having excellent heat resistance is preferable in the film-forming step, and examples thereof include an anthraquinone-based chemical dye. As for the color tone, when the purpose is to prevent the light piping phenomenon, gray dyeing as seen in a general silver halide photographic light-sensitive material is preferable. The dyes may be used alone or in combination of two or more. As a commercial product, manufactured by Mitsubishi Kasei:
Diaresin, Bayer: MACROLEX
The objectives can be achieved by using these dyes alone or by appropriately mixing them.

Hereinafter, specific examples of the present invention will be described.
Embodiments of the present invention are not limited to these.

[0107]

EXAMPLES [Evaluation Method] <Evaluation of Magnetic Recording Layer> Evaluation methods of the magnetic output of the transparent magnetic recording layer, the orientation ratio of the upper and lower layers, turbidity, scratch resistance and dynamic friction coefficient are shown below.

<< Magnetic Output (Electromagnetic Conversion Characteristics) >> By using a magnetic head for an audio tape recorder, at a transport speed of 100 mm / sec, 10 k in the longitudinal direction of the magnetic recording medium.
A square wave of Hz is recorded at an optimum recording current, reproduced at the same conveyance speed of 100 mm / sec, and the reproduced output at that time is evaluated.

The value of the magnetic output was determined in dB assuming that the longitudinal direction of the following standard sample was 0 dB.

<< Orientation Ratio >> The surface (upper layer side) of the transparent magnetic recording layer is observed and photographed with a scanning electron microscope. The photograph is processed by an image analyzer. Change the observation point 1
Processing is performed for zero or more visual fields to determine the orientation distribution. The surface on the lower layer side is removed by polishing the upper transparent magnetic recording layer,
The lower layer is exposed, and the same photographing and image analyzer processing are performed. The processed data is obtained by the above equations (1) and (2).

<< Optical Density >> Konica Sakura Densitometer P
A method of calculating the absorption of light by the magnetic recording layer, by using a DA-65 and transmitting a light of 436 nm wavelength perpendicularly to the magnetic recording layer using a filter transmitting blue light.

<< Scratch resistance >> Using a surface property measuring device HEIDON trigear type 14DR, in a measuring environment of 23 ° C. and 55% RH, a stainless steel ball (10 mmφ) needle was 50 g.
And apply a sliding force of 100 at a speed of 5 cm / sec.
Reciprocation is repeated, and the degree of damage is evaluated according to the rank shown below.

5: No damage 4: Slight sliding marks 3: Sliding marks 2: Scratch 1: Film peeling

<< Dynamic Coefficient of Friction >> A sample before development was heated at 23 ° C.
After adjusting the humidity for one day and night in an environment of 55% RH, the HEID
The dynamic friction coefficient between a square polystyrene plate having a side of 1 cm and a transparent magnetic recording layer under a load of 100 g is measured by ON-14DR.

[Preparation of support having an undercoat layer formed thereon] A polyethylene-2,6-naphthalate film support (having a thickness of 85
μm) is subjected to a corona discharge treatment at 10 W / m ² · min, and one side is coated with the undercoat layer coating solutions U-1 and U-
2 was sequentially applied from the support side to a dry film thickness of 0.8 μm and 0.1 μm, and the other surface of the support was coated with the undercoat layer coating solutions U-3 and S-1 having the following composition. The coating was applied in order from the body side to a dry film thickness of 0.1 μm and 0.3 μm to prepare a support having an undercoat layer having an antistatic function. Hereinafter, “parts” of each material in the composition indicates “parts by weight” unless otherwise specified.

<Undercoat layer coating liquid U-1> Butyl acrylate / t-butyl acrylate / styrene / 2-hydroxyethyl methacrylate copolymer latex liquid (weight composition ratio = 30/20/25/25, solid content (30%) 270 parts Surfactant (A-1) 0.5 part Hardener (H-1) 1 part Pure water 730 parts <Undercoat layer coating liquid U-2> Styrene / maleic acid copolymer latex liquid (Weight ratio 50/50, solid content 5%) 100 parts Surfactant (A-1) 0.5 part Hardener (H-2) 0.1 part Matting agent (silica particles having an average particle diameter of 3 μm) 0.5 parts Pure water 900 parts <Undercoat layer coating liquid U-3> Epocross K-2020E (Nippon Shokubai Co., Ltd., solid content 40%) 200 parts Surfactant (A-1) 0.5 parts Pure water 800 parts <Undercoat layer coating liquid S-1> Tin oxide fine powder (average particle (Diameter 0.1 μm) (manufactured by Ishihara Sangyo Co., Ltd .: SN100P) 44 parts Water dispersion K (described below) 109 parts Surfactant (A-1) 0.4 part Pure water 1000 parts (Preparation of water dispersion K) 60 mol% of dimethyl terephthalate, 30 mol% of dimethyl isophthalate, 10 mol% of sodium salt of dimethyl 5-sulfoisophthalate as a dicarboxylic acid component, and 50 mol% of ethylene glycol and 50 mol% of diethylene glycol as glycol components are copolymerized by a conventional method. did. This copolymer K was dissolved in hot water at 95 ° C for 3 hours.
After stirring for 15 hours, a 15% by weight aqueous dispersion K was obtained.

[0117]

Embedded image

[Preparation of Transparent Magnetic Recording Layer Coating Solution] <Preparation of Transparent Magnetic Recording Layer Coating Solution M-1> First, a magnetic agent composition solution P-1 having the following composition was stirred and mixed, and then dispersed in a sand mill.

<< Magnetic Agent Composition P-1 >> Cobalt-containing γ-iron oxide (average major axis length 0.12 μm, minor axis length 0.015 μm, Fe ²⁺ / Fe ³⁺ = 0.2, specific surface area 40 m ² / G, Hc = 750 Oe) 7 parts α-alumina (average particle size 0.2 μm) 5 parts Polyurethane (molecular weight 30,000, containing two sulfonic acid groups in one molecule) (manufactured by Toyobo Co., Ltd., NK-7) 1 part Methyl ethyl ketone 10 parts Cyclohexanone 3 parts The above-mentioned magnetic agent composition liquid P-1 was diluted with the following resin solution for dilution LD-
The mixture was diluted with 1, stirred and mixed.

<< Dilution Resin Solution LD-1 >> Cellulose diacetate 89 parts Cyclohexanone 600 parts Acetone 600 parts After this mixed solution was further dispersed by a sand mill, coronate 3041 (solid content: 50%, manufactured by Nippon Urethane Co., Ltd.) was added. 2
After adding 0 parts and stirring, the mixture was filtered with a filter to prepare a coating solution M-1 for a transparent magnetic recording layer. Transparent magnetic recording layer coating solution M
-1 was measured with a BL viscometer (manufactured by Tokimec Co., Ltd.). 2
Shear rate 15 s measured at 60 rpm using a rotor
The viscosity at ec ^-1 was 160 cps.

<Preparation of Transparent Magnetic Recording Layer Coating Solution M-2> The same process as for the transparent magnetic recording layer coating solution M-1 was performed except that the diluting resin solution LD-1 was changed to the diluting resin solution LD-2. Then, a coating solution M-2 for a transparent magnetic recording layer was prepared.

<< Dilution Resin Solution LD-2 >> Cellulose Diacetate 89 parts Cyclohexanone 900 parts Acetone 900 parts The transparent magnetic recording layer coating solution M-2 was sheared at a shear rate of 1 in the same manner as described above.
The viscosity at 5 sec ^-1 was 63 cps.

<Preparation of Transparent Magnetic Recording Layer Coating Solution M-3> The same procedure as for the transparent magnetic recording layer coating solution M-1 was carried out except that the diluting resin solution LD-1 was changed to the diluting resin solution LD-3. Then, a coating solution M-3 for a transparent magnetic recording layer was prepared.

<< Resin Diluent Solution LD-3 >> Cellulose diacetate 89 parts Cyclohexanone 950 parts Acetone 950 parts The transparent magnetic recording layer coating solution M-3 was subjected to a shear rate of 1 in the same manner as described above.
The viscosity at 5 sec ^-1 was 55 cps.

<Preparation of Transparent Magnetic Recording Layer Coating Solution M-4> The same process as for the transparent magnetic recording layer coating solution M-1 was performed except that the diluting resin solution LD-1 was changed to the diluting resin solution LD-4. Then, a coating solution M-4 for a transparent magnetic recording layer was prepared.

<< Dilution Resin Solution LD-4 >> Cellulose diacetate 89 parts Cyclohexanone 1200 parts Acetone 1200 parts The transparent magnetic recording layer coating solution M-4 was subjected to a shear rate of 1 in the same manner as described above.
The viscosity at 5 sec ^-1 was 13 cps. No. in BL type viscometer. The measurement was performed at 60 rpm using one rotor.

<Preparation of Transparent Magnetic Recording Layer Coating Solution M-5> The same steps as for the transparent magnetic recording layer coating solution M-1 were carried out except that the diluting resin solution LD-1 was changed to the diluting resin solution LD-5. Then, a coating solution M-5 for a transparent magnetic recording layer was prepared.

<< Resin Diluent Solution LD-5 >> Cellulose diacetate 89 parts Cyclohexanone 1250 parts Acetone 1250 parts The transparent magnetic recording layer coating solution M-5 was subjected to a shear rate of 1 in the same manner as described above.
The viscosity at 5 sec ^-1 was 7 cps. Using a BL adapter with a BL viscometer (manufactured by Tokimec Co., Ltd.)
It was measured at 12 rpm.

[Preparation of Wax-Containing Transparent Magnetic Recording Layer Coating Solution] <Preparation of Wax-Containing Transparent Magnetic Recording Layer Coating Solution WK-1><< Preparation of Wax Composition Solution >> The following wax composition solution E-1 was mixed and heated. The wax was heated and dissolved.

<< Wax Composition Liquid E-1 >> Carnauba wax No. 1 1 (manufactured by Kato Yoko Co., Ltd.) 10 parts Cyclohexanone 50 parts Acetone 50 parts << Preparation of Wax Emulsion YE-1 >> The following solvent composition Y-1 is mixed with the above wax composition liquid E-1 and cooled to form an emulsion. The wax was precipitated from the mixture to prepare a wax emulsion YE-1.

<< Solvent Composition Y-1 >> Cyclohexanone 150 parts Acetone 150 parts The following magnetic agent composition liquid P was added to the following resin solution for dilution LD-6.
-1 and the wax emulsion YE-1 were mixed and stirred.

<< Resin Solution for Dilution LD-6 >> Cellulose diacetate 89 parts Cyclohexanone 400 parts Acetone 400 parts
20 (solid content: 50%), stirred, filtered through a filter, and applied to a wax-containing transparent magnetic recording layer coating solution W
K-1 was obtained. Wax-containing coating solution for transparent magnetic recording layer WK
The average particle size of the wax in -1 was 1.0 μm. The wax-containing transparent magnetic recording layer coating solution WK-1 was subjected to the same BL type viscometer as No. The viscosity at a shear rate of 15 sec ^-1 measured at 60 rpm using two rotors was 165 cps.

<Wax-Containing Transparent Magnetic Recording Layer Coating Solution WK>
Preparation of -2> Wax-containing except that the resin solution for dilution LD-6 was changed to the resin solution for dilution LD-7 and the dispersion time was 1.2 times that of the wax-containing transparent magnetic recording layer coating solution WK-1. A wax-containing transparent magnetic recording layer coating solution WK-2 was prepared in the same manner as the transparent magnetic recording layer coating solution WK-1.

<< Dilution Resin Solution LD-7 >> Cellulose diacetate 89 parts Cyclohexanone 700 parts Acetone 700 parts The wax-containing transparent magnetic recording layer coating solution WK-2 had an average particle diameter of 1.0 μm. The viscosity of the wax-containing transparent magnetic recording layer coating solution WK-2 at a shear rate of 15 sec ^-1 was 65 cps (BL viscometer, No. 2).
Rotor measured at 60 rpm).

<Wax-Containing Transparent Magnetic Recording Layer Coating Solution WK>
Preparation of -3> Wax-containing except that the resin solution for dilution LD-6 was changed to the resin solution for dilution LD-8 and the dispersion time was 1.3 times that of the wax-containing transparent magnetic recording layer coating solution WK-1. Similarly to the transparent magnetic recording layer coating liquid WK-1, a wax-containing transparent magnetic recording layer coating liquid WK-3 was prepared.

<< Dilution Resin Solution LD-8 >> Cellulose diacetate 89 parts Cyclohexanone 1000 parts Acetone 1000 parts The wax-containing transparent magnetic recording layer coating liquid WK-3 had an average particle diameter of 1.0 μm. The viscosity of the wax-containing transparent magnetic recording layer coating solution WK-3 at a shear rate of 15 sec ^-1 was 15 cps (BL viscometer, No. 1).
Rotor measured at 60 rpm).

<Wax-Containing Transparent Magnetic Recording Layer Coating Solution WK>
Preparation of -4> Wax-containing except that the resin solution for dilution LD-6 was changed to the resin solution for dilution LD-9 and the dispersion time was 1.32 times that of the wax-containing transparent magnetic recording layer coating solution WK-1. Similarly to the transparent magnetic recording layer coating liquid WK-1, a wax-containing transparent magnetic recording layer coating liquid WK-4 was prepared.

<< Dilution Resin Solution LD-9 >> Cellulose diacetate 89 parts Cyclohexanone 1050 parts Acetone 1050 parts The wax-containing transparent magnetic recording layer coating liquid WK-4 had an average particle diameter of 1.0 μm. The viscosity of the wax-containing transparent magnetic recording layer coating solution WK-4 at a shear rate of 15 sec ^-1 was 8 cps (measured with a BL viscometer and a BL adapter at 12 rpm).

<Preparation of Wax-Containing Layer Coating Solution WA-1><< Wax Dispersion YB-1 >> 1 (solid content: 40% by weight) 10 parts C ₁₀ H ₂₁ (CH ₂ CH ₂ O) ₁₈ H 5 parts Cyclohexanone 90 parts The above composition was dispersed, and the particle size of carnauba wax was adjusted to 1.
After the dispersion liquid YB-1 having a thickness of 0 μm, the dispersion liquid was diluted with the following diluent to obtain a wax-containing coating liquid WA-1.

<< Dilution Solution LD-10 >> Cyclohexanone 90 parts Acetone 400 parts Cellulose diacetate 22 parts <Standard sample> Undercoat layer S-1 of the support having the undercoat layer formed thereon
A transparent magnetic recording layer coating solution M-1 was coated on the substrate using an extrusion coater having a slitter so that the support tension was 6 kg / mm, the coating speed was 30 m / min, and the dry film thickness was 1.2 μm. After coating and drying under the conditions of a coating solution flow rate and a coating shear rate of 1.2 × 10 ⁴ sec ⁻¹ , the raw material after coating is left in an oven at 50 ° C. for 5 days to sufficiently perform a crosslinking reaction of isocyanate. (Since the isocyanate treatment is performed in each of the following Examples and Comparative Examples, this description is omitted.)

Example 1 A transparent magnetic recording layer coating solution M-1 was provided on the undercoat layer S-1 of the support on which the undercoat layer had been formed. 19262
No. 7, using an extrusion coater shown in FIG. 3, a support tension of 6 kg / mm width and a coating speed of 30 m / m
min, the flow rate of the coating solution such that the dry film thickness of the lower layer coating solution M-1 is 1.1 μm, and the coating shear rate is 1.3 × 10 ⁴ sec.
Under the condition of c ^-1 and the dry film thickness of the upper layer coating solution M-1 of 0.
Coating solution flow rate, coating shear rate 1.4 × to be 1 μm
The wet-on-wet simultaneous multi-layer coating is performed under the condition of 10 ⁵ sec ⁻¹ , and after drying, the raw material after coating is reduced to 50
The sample was allowed to stand in an oven at a temperature of 5 ° C. for 5 days so that the crosslinking reaction of the isocyanate was sufficiently performed to obtain a sample.

Example 2 A sample was prepared in the same manner as in Example 1 except that the coating liquid for the upper transparent magnetic recording layer was M-2, and the conditions were changed to a coating shear rate of 9.5 × 10 ⁴ sec ^−1. did.

Example 3 A sample was prepared in the same manner as in Example 1, except that the coating liquid for the upper transparent magnetic recording layer was M-4, and the conditions were changed to a coating shear rate of 7.1 × 10 ⁴ sec ^−1. did.

[Comparative Example 1] The coating liquid for the lower transparent magnetic recording layer was M-3 and the coating liquid for the upper transparent magnetic recording layer was M-5. Under the conditions of flow rate and coating shear rate of 9.5 × 10 ³ sec ⁻¹ ,
A sample was prepared in the same manner as in Example 2 except that the flow rate of the coating solution and the shear rate of the coating were changed to 1.6 × 10 ⁴ sec ^-1 so that the dry film thickness of the upper layer coating solution was 0.4 μm. did.

Table 1 shows the results of measuring and evaluating the orientation ratio, the electromagnetic conversion characteristics of the magnetic recording layer, the optical density (turbidity), the scratch resistance and the dynamic friction coefficient of Examples 1 to 3 and Comparative Example 1.
Shown in

[0146]

[Table 1]

(Results) The upper transparent magnetic recording layer coating liquid having a viscosity of 10 cps or more and the lower transparent magnetic recording layer coating liquid having a viscosity of 10 cps or more at a shear rate of 15 sec ^-1 was applied (the upper layer was 2 cps). The sample coated at × 10 ⁴ sec ⁻¹ or more) had a higher orientation ratio of the upper layer on the upper layer side, and also had good electromagnetic conversion characteristics. On the other hand, the viscosity of the coating liquid for the upper transparent magnetic recording layer was as low as 7 cps.
Comparative Example 1, which was applied at 1.6 × 10 ⁴ sec ⁻¹ or less at × 10 ⁴ sec ⁻¹ , did not have orientation and had poor electromagnetic conversion characteristics.

[Example 4] Coating solution M for lower transparent magnetic recording layer
The coating conditions W- ¹ of the wax-containing upper transparent magnetic recording layer WK-2 were set such that the flow rate of the coating solution and the coating shear rate were 7.1 × 10 ³ sec ^-1 so that the dry film thickness was 1.0 μm.
Using an extruder coater having two slits at a coating solution flow rate and a coating shear rate of 2.4 × 10 ⁴ sec ^-1 such that the dry film thickness becomes 0.2 μm, the support body tension is 6 kg / mm width. A wet-on-wet simultaneous layering is performed on a support having a coating speed of 15 m / min,
After drying, a sample was prepared in the same manner as in Example 1, except that the sample was passed through a heat treatment zone at 100 ° C. for 1 minute.

Example 5 The coating liquid for the wax-containing upper transparent magnetic recording layer was WK-1, and the coating liquid flow rate and the coating shear rate were 1.4 × 10 ⁵ sec so that the dry film thickness was 0.1 μm.
A sample was prepared in the same manner as in Example 4, except that the coating was changed to c- ¹ .

[Comparative Example 2] The coating liquid for the lower transparent magnetic recording layer was defined as M-1, and the coating shear rate was set to 1.3 × 10 ⁴ sec ^-1 at a coating liquid flow rate such that the dry film thickness became 1.1 μm. ,
One layer is applied to a support having a support tension of 6 kg / mm width and a coating speed of 30 m / min with an ecruder coater having one slit, dried, and then a wax-containing upper transparent magnetic recording layer coating liquid WK-1 is dried. An extruder coater having one slit so as to have a thickness of 0.1 μm and a coating shear rate of 1.4 × 10 ⁵ sec ⁻¹ is applied on the magnetic recording layer coated with M-1 by wet-on-coating.
Although the coating was performed by a dry method, coating non-uniformity, coating unevenness, liquid dripping, and the like occurred, and the coating could not be uniformly performed, and a sample could not be prepared.

Comparative Example 3 The coating shear rate of the wax-containing upper transparent magnetic recording layer coating solution WK-1 was 2.1 × 10 ⁴ s.
Coating was carried out in the same manner as in Comparative Example 2 except for changing to ec ^-1 .
Coating non-uniformity, coating non-uniformity, liquid dripping, etc., occurred, the coating could not be applied uniformly, and a sample could not be prepared.

Examples 4 and 5 and Comparative Examples 2 and 3
Table 2 shows the evaluation results.

[0153]

[Table 2]

(Result) 2.4 × 10 ⁴ sec ⁻¹ and 1.4 × 1 with the wax-containing transparent magnetic recording layer coating solution as the upper layer.
0 ⁵ sec ^-1 shear rate simultaneous multilayer sample in a wet-on-wet method, the high layer of the orientation ratio, particularly Example 5 is very high orientation ratio was excellent electromagnetic characteristics. On the other hand, in the comparative example applied by the wet-on-dry method, the upper layer was dried on the lower layer at a shear rate of 2 × 10 ⁴ sec ^-1 or more. And no sample could be obtained.

Example 6 The coating liquid for the lower transparent magnetic recording layer was M-2, the flow rate of the coating liquid was such that the dry film thickness was 0.9 μm, and the coating shear rate was 2.5 × 10 ⁴ sec ⁻¹ . Further, the coating liquid for the magnetic recording layer containing the wax upper layer is WK-3,
The coating liquid flow rate, the coating shear rate is 2.4 × 10 ⁴ sec ⁻¹ and the coating speed is 30 m / m so that the dry film thickness becomes 0.3 μm.
A sample was prepared in the same manner as in Example 4 except that the sample was changed to “in”.

[Comparative Example 4] The coating liquid for the lower transparent magnetic recording layer was defined as M-1, the flow rate of the coating liquid was set such that the dry film thickness became 0.9 μm, and the coating shear rate was set to 4.7 × 10 ⁴ sec ^-1 . In addition, the wax-containing upper magnetic recording layer coating solution is WK-4,
A sample was prepared in the same manner as in Example 6, except that the flow rate of the coating solution and the coating shear rate were changed to 1.6 × 10 ⁴ sec ^-1 so that the dry film thickness became 0.4 μm.

[Comparative Example 5] The lower transparent magnetic recording layer coating solution was M-3, and the wax upper layer-containing magnetic recording layer coating solution was WK-2.
A sample was prepared in the same manner as in Comparative Example 4, except that

Table 3 shows the evaluation results of the samples of Example 6 and Comparative Examples 4 and 5.

[0159]

[Table 3]

(Results) In Comparative Examples 4 and 5, the coating liquid for the lower transparent magnetic recording layer was applied at a shear rate of 4.7 × 10 ⁴ sec ⁻¹ , and the coating liquid for the upper transparent magnetic recording layer containing wax was applied.
It is a sample in which the orientation ratio of the lower layer exceeds the orientation ratio of the upper layer, which is simultaneously layered by a wet-on-wet method at × 10 ⁴ sec ⁻¹ or less. In Comparative Example 4, the viscosity of the upper layer coating solution at a shear rate of 15 sec ^-1 was 60 cps.
Comparative Example 5 has a viscosity of 10 cps at a shear rate of 15 sec ^-1 of the lower layer coating solution.
It is a sample in the case of the following. Both samples had the same electromagnetic conversion characteristics as the standard sample, and no effect was observed. In addition, due to the influence of the mixing of the upper and lower layers, an increase in the optical density and a remarkable increase in the dynamic friction coefficient are observed, which is not preferable. Example 6 is a sample in which the viscosity of the upper layer coating solution is 10 cps or more, and the viscosity of the lower layer coating solution is 60 cps or more. No mixing of the upper and lower layers occurs, the optical density increases, and the dynamic friction coefficient does not increase.
Electromagnetic conversion characteristics are also increasing.

Example 7 Lower transparent magnetic recording layer coating solution M
-1 is set as the coating liquid flow rate and the coating shear rate is 2.4 × 10 ⁴ sec ^-1 so that the dry film thickness becomes 1.0 μm, and the wax-containing upper transparent magnetic recording layer coating liquid WK-1 is used as the dry film. Assuming that the thickness of the coating solution is 0.2 μm and the coating shear rate is 1.2 × 10 ⁵ sec ⁻¹ , the support tension is 9 k.
A sample was prepared in the same manner as in Example 4, except that the sample was applied to the support at a g / mm width and an application speed of 50 m / min.

[Example 8] Coating solution M for lower transparent magnetic recording layer
-1, the coating shear rate is 4.7 × 10 ⁴ sec ⁻¹ , and the wax-containing upper transparent magnetic recording layer coating solution WK
-1, the coating shear rate is 2.4 × 10 ⁵ sec ⁻¹ , the support tension is 12 kg / mm width, and the coating speed is 100 m / mi.
A sample was prepared in the same manner as in Example 7, except that n was applied to the support.

[Example 9] Coating solution M for lower transparent magnetic recording layer
-1, the coating shear rate is 4.3 × 10 ⁴ sec ⁻¹ , and the wax-containing upper transparent magnetic recording layer coating solution WK
-1, the coating shear rate is 4.7 × 10 ⁵ sec ⁻¹ , the support tension is 12 kg / mm width, and the coating speed is 100 m / mi.
A sample was prepared in the same manner as in Example 7, except that n was applied to the support.

[Comparative Example 6] Coating solution M for lower transparent magnetic recording layer
-1 is set to a coating liquid flow rate and a coating shear rate of 2.4 × 10 ⁴ sec ^-1 such that the dry film thickness becomes 1.1 μm. 1μ
m, coating shear rate 1.2 × 10
^A sample was prepared in the same manner as in Example 7, except that the support was applied to the support at ⁵ sec ^{-1 with} a support tension of 9 kg / mm width and an application speed of 50 m / min.

Further, the following silver halide emulsion layer and the like were coated to prepare a silver halide color photographic light-sensitive material.

[Preparation of silver halide photographic light-sensitive material] On the undercoat layer U-2 opposite to the surface having the magnetic recording layer, 25 W
/ M ² · min after corona discharge,
A multilayer silver halide color photographic light-sensitive material having the emulsion layer constitution of Sample 1, Sample 101 described in No. 34858 was prepared.

The gelatin was 13.7 g, 0.3 to 0.4 μm per m ² of the coated silver halide emulsion layer of the sample.
The silver halide grains of m and 0.7 to 0.8 μm each had 2.3 g, the amount of high boiling point solvent was 2.8 g, and the film thickness was 27 μm.

The silver halide color photographic light-sensitive material was subjected to the following development processing.

<Development> The prepared silver halide color photographic light-sensitive material is developed according to the following processing steps.

Processing step Processing time Color development 3 minutes 15 seconds Bleaching 6 minutes 30 seconds Rinse 2 minutes 10 seconds Fixed 4 minutes 20 seconds Rinse 3 minutes 15 seconds Stabilization 1 minute 05 seconds Processing solutions used in each step The composition is as follows.

<< Color Developer >> Diethylenetriaminepentaacetic acid 1.0 g 1-hydroxyethylidene-1,1-diphosphonic acid 2.0 g sodium sulfite 4.0 g potassium carbonate 30.0 g potassium bromide 1.4 g potassium iodide 1.3 mg Hydroxylamine sulfate 2.4 g 4- (N-ethyl-N-β-hydroxyethyl) amino-2-methylaniline sulfate 4.5 g Add water to make 1 liter, and adjust to pH 10.0.

<< Bleaching Solution >> Ferric ammonium ethylenediaminetetraacetate 100.0 g Disodium ethylenediaminetetraacetate 10.0 g Ammonium bromide 150.0 g Ammonium nitrate 10.0 g Water was added to adjust to 1 liter, and the pH was adjusted to 6.0. I do.

<< Fixing solution >> Disodium ethylenediaminetetraacetate 1.0 g Sodium sulfite 4.0 g Ammonium thiosulfate (70%) 175.0 g Sodium bisulfite 4.6 g Water is added to 1 liter to adjust the pH to 6.6.

<< Stabilizing Solution >> Formalin (40%) 2.0 mg Polyoxyethylene-p-monononylphenyl ether (average degree of polymerization: 10) 0.3 g Add water to make 1 liter.

The samples of Examples 7 to 9 and Comparative Example 6 were similarly evaluated, and the results are shown in Table 4 below.

[0176]

[Table 4]

(Results) Examples 7 to 9 were samples in which all the necessary conditions of the present invention were incorporated, and any evaluation results as magnetic recording media were good, and the best results of the present invention were obtained. In Comparative Example 6, the upper layer was a layer composed of only the wax and the binder, and had good optical density, scratch resistance and dynamic friction coefficient, but had poorer electromagnetic conversion characteristics than the standard sample. It was found that the wax-containing upper magnetic recording layer of the present invention produced by the method of the present invention had excellent properties. The magnetic recording layer after development processing of the silver halide photographic light-sensitive material of the present invention, in which a silver halide emulsion layer or the like is coated on the opposite side of the support of these magnetic recording media, can be developed. No deterioration of each performance was observed.

[0178]

The magnetic recording medium of the present invention is excellent in magnetic input / output characteristics, transparency, scratch resistance and slipperiness by applying a mechanical orientation to an upper layer by setting a suitable shear rate at the time of coating. A silver halide photographic material having a recording layer and excellent in magnetic properties and transparency for APS can be provided.

Claims (12)

[Claims] When a transparent magnetic recording layer of at least two layers is coated on one surface of a support by a wet-on-wet method, the transparent magnetic recording layer is adjacent to the lower transparent magnetic recording layer coating solution on the support side. A method for producing a magnetic recording medium, characterized in that the shearing rate applied to the coating liquid for the upper transparent magnetic recording layer is 2 × 10 ⁴ sec ⁻¹ or more. 2. A method for producing a magnetic recording medium having at least two transparent magnetic recording layers on one surface of a support, wherein the upper transparent magnetic recording layer is adjacent to the lower transparent magnetic recording layer coating solution on the support side. It is characterized in that the orientation ratio of the magnetic powder in the upper transparent magnetic recording layer is higher than that of the magnetic powder in the lower transparent magnetic recording layer by applying the recording layer coating solution in a multi-layer manner by a wet-on-wet method. A method for manufacturing a magnetic recording medium. 3. The method of manufacturing a magnetic recording medium according to claim 1, wherein the orientation ratio of the magnetic powder in the upper transparent magnetic recording layer is higher than the orientation ratio of the magnetic powder in the lower transparent magnetic recording layer. 4. A method for simultaneously applying at least two transparent magnetic recording layers on one surface of a support by multi-layer coating, the viscosity of a lower transparent magnetic recording layer coating liquid applied on the side close to the support being determined by the shear rate. not less than 60cps when 15 sec ^-1, and a method of manufacturing a magnetic recording medium characterized by applying the viscosity of the upper transparent magnetic recording layer coating solution with adjacent to the air side as 10cps or more when the shear rate of 15 sec ^-1 . 5. The method for producing a magnetic recording medium according to claim 4, wherein the application is carried out at a shear rate of 2 × 10 ⁴ sec ⁻¹ or more for the coating liquid for the upper transparent magnetic recording layer. 6. The method according to claim 5, wherein the orientation ratio of the magnetic powder in the upper transparent magnetic recording layer is higher than the orientation ratio of the magnetic powder in the lower transparent magnetic recording layer. 7. The coating liquid for the upper and lower transparent magnetic recording layers, wherein the dry film thickness of the upper transparent magnetic recording layer is 1% of the dry film thickness of the entire magnetic recording layer.
The method for producing a magnetic recording medium according to any one of claims 1 to 6, wherein the coating is performed so as to be 30% or less. 8. The method for manufacturing a magnetic recording medium according to claim 1, wherein the upper transparent magnetic recording layer is an upper transparent magnetic recording layer containing wax. 9. The method according to claim 8, wherein the upper transparent magnetic recording layer containing the wax forms an uppermost layer. 10. A coating solution for an upper transparent magnetic recording layer containing a wax adjacent to a coating solution for a lower transparent magnetic recording layer on the support side, which is adjacent to the coating solution for a lower transparent magnetic recording layer on the support, is applied in a multi-layer manner by a wet-on-wet method. A method for manufacturing a magnetic recording medium, comprising: 11. A magnetic recording medium manufactured by the method according to claim 1. Description: 12. A silver halide photographic material comprising a silver halide emulsion layer on the side of the support opposite to the side having the magnetic recording layer of the magnetic recording medium according to claim 11.